Heat treatment of saws, etc.



2 Sheets-Sheet l 1 fiver? f I I I I I l I I I I I I I l I I l I I l I I I I I I I I I I l I I I I I I I I I June 11, 1935. A. M.'REMINGTON HEAT TREATMENT OF SAWS ETC Filed Dec 30, 1931 IP w June 11, 1935.

A. M. REMINGTON HEAT TREATMENT OF SAWS, ETC

Filed Dec. 30, 1931 2 Sheets-Sheet 2 r Z 22 1167a 2607; A [fa/W225; Z072 A @7 75.

Patented June 11, 1935 UNITED STATES PATENT OFFICE HEAT TREATMENT OF SAWS, ETC.

Alfred M. Remington, Fitchburg, Mass., assignor to Simonds Saw and Steel Company, Fitchburg, Mass, a corporation of Massachusetts Application December 30, 1931, Serial No. 583,819 3 Claims. (Cl. 219-11) This invention relates particularly to saw tendetermined the relationships, thereafter it will sioning and aims to provide a method and apbe necessary merely to adjust the speed and ourparatus for uniformly heating an annular porrent in accordance with the prior observations. tion of a circular saw blade or the like, thereby Apparatus for carrying out my method is to effect a uniform heat treatment of the same shown in the accompanying drawings wherein which will tension its periphery without injur- Fig. 1 is a side elevation, partly in section and ing or substantially. changing the character of with parts broken away, of one type of saw tenthe remaining portion of the blade so treated, sioning apparatus;

A further object is to provide an apparatus Fig. 2 is a section on the line 2--2 of Fig. 1;

which may be adjusted to accommodate saws of and different sizes. Fig. 3 is a view similar to Fig. 1 of a modified Heretofore it has been proposed to tension the type of apparatus. periphery of circular saws by clamping the saw Referring to the drawings, particularly Figs. 1 between annular heating units which contact and 2, the apparatus shown therein comprises an with the saw throughout an annular area someelongated base I to which is rigidly secured the what removed from the periphery of the saw, bed 2 and bracket 3. The bed preferably comand subsequently cooling the saw in well known prises a pair of channel irons 4 and 5 disposed manner to have the periphery under tension cirin spaced relation, as shown in Fig. 2, to provide a cumferentially of the saw. This prior method longitudinal opening. A carriage 6 is slidably has been unsatisfactory for various reasons, mounted on the inwardly directed flanged por- 20 chiefly because different sized units had to be tions of the channel irons which serve as guides. provided for saws of different diameters, the The lower portion of the carriage projects into units were costly to make and keep in repair, the the opening and is provided with a longitudinally saws could not be observed while being heated, extending threaded opening which receives one and it was difficult, if not impossible to produce end of screw shaft 8, the opposite end of the uniform results in successive saws and somescrew shaft being journaled in plate 9 secured to times throughout the circumference of individthe end of the bed. By means of the hand crank ual saws. I 0 fast to the screw shaft, the position of the In accordance with my invention I provide carriage, relative to the bracket 3, may be admeans for passing electric current through an justed to accommodate saws of different diame- 30 annular portion of a saw blade adjacent to its ters and to vary the location of the electrodes relperiphery for a predetermined period of time, ative to the axis of each saw for the purpose of thereby heating the same to the required temprogressively varying the radius of the annular perature to effect heat treatment which will rezone to be heated.

suit in tensioning the periphery of the blade. The upper part of the carriage is provided with 35 This is accomplished by producing relative ana horizontal platform l2 having a. facing [3 of nular movement, about the axis of the circular suitable insulating material. A bolt or threaded saw, between the saw and a pair of electrodes pivot l4 projects upwardly from the central pordisposed on opposite sides of the saw, the election of the carriage and is firmly held in positrodes being connected with a source of current tion by the set screw l5.

by means of which a predetermined current is The bracket 3 preferably comprises a two-piece passed through the blade to heat the annular casting having its upper part rigidly secured to portion adjacent the path traced by the elec its lower part by bolts I6. A drive shaft I8 is trodes during said relative rotation. journaled in the lower part of bracket 3 and the As the heating effect depends primarily upon roller electrode 20 is keyed or otherwise suitably 45 the strength of the current, the time, and the secured thereto. As shown in Fig. 1, the periphcharacter of the saw blade, in order to produce cry of roller electrode 20 is tangent to the plane the degree of heat necessary to tension the peof the top surface of the insulating plate l3. The riphery of the blade it is proposed to regulate upper portion of the bracket is provided with an the speed of rotation of the blade for a definite overhanging arm l9 having a vertically extend- 50 current, or to regulate the current for a definite ing opening in which the rod 22 is slidably mountspeed of rotation, or to regulate both speed and ed. Integral with the lower end of rod 22 is a current concomitantly. Preliminary experiments yoke 23 in which the roller electrode 2| is suitmay be necessary to determine these factors for ably journaled. Preferably the hearings in which a particular type of saw blade, but having once each of the electrodes are journaled are provided 55 with insulating sleeves or other suitable means providing insulation between the respective electrodes and the yoke and bracket. The coiled compression spring 25 circumposed about the rod 22 engages the arm l9 and yoke 23 and normally urges the electrode 2| downwardly toward the electrode is, which is disposed in vertical alignment therewith. The vertical movement of electrode 2! is limited by the pin 26 which is carried by rod 22 and projects into the slots 21 of arm l9. Electrical conductors 30 and 3| connect the electrodes 20 and M respectively, with any suitable source of current, the electrode 2! preferably being connected to the positive terminal.

In operating the apparatus a saw 35 to be tensioned is positioned as shown in Fig. l with its opposite faces interposed between and in contact with the electrodes 20 and 2|. The flanged insulating collar 32 fitting around the pivot l4 provides a suitable insulation between the saw and the pivot and also serves as a bearing for the saw. The annular flange of the collar is spaced from the plate l3 sufiiciently to prevent binding the saw when the screw clamp 34 is tightened, thus permitting free rotation of the saw without objectionable play.

Thus the saw is rotated by the roller electrode so while current is passed through the annular zone adjacent the path traced on the saw by the electrodes. By using a heavy current the zone may be heated in one revolution, but I prefer to use a lighter current and rotate the saw many times, thereby gradually bringing the annular zone to the desired temperature. After the zone is heated it is cooled in the usual way to leave the periphery under tension.

The modification shown in Fig. 3 diifers from thatof Figs. 1 and 2 chiefly in that the saw is rotated independently of the electrodes, in which case the electrodes may be in the form of rollers or sliding shoes. In this embodiment the bed 4| comprises a pair of spaced channel irons which extend throughout the entire length of the base 40 and are rigidly secured thereto. The support 45, secured to the end of the bed, is provided with a vertically extending central opening in which the upper part of shaft 46 is journaled', the lower end of the shaft being journaled in the base 40. A turntable 41, keyed or otherwise fixed to shaft 46, is provided with a facing 48 of insulating material. The shaft 46 projects upwardly beyond the facing and is provided with a threaded end which receives the screw clamp 49 by means of which the saw 50 is firmly clamped between the flanged insulating collar 5| and the turntable. Preferably ball bearings 52 are provided between the turntable and the upper surface of the support. The worm wheel 54 fast to shaft 46 engages the worm 55 mounted on a driving shaft 56 journaled in the bed.

The bracket 60 is of similar construction to the corresponding member shown in Figs. 1 and 2, but is slidably mounted on the bed 4 I. The lower part of the bracket is provided with a depending portion 6| having a longitudinal threaded opening which receives the screw shaft 62. The outer end of the screw shaft is journaledin plate 53 secured to the end of the bed and is actuated by the hand crank 64 to adjust the longitudinal position of the bracket relative to the support 45.

In place of the roller electrodes shown in the previously described embodiment, shoe electrodes 65 and 66 have been substituted. The electrode 65 is mounted in recess 51 in the lower part of the bracket and is disposed with its contacting surface in the plane of the upper surface of the insulated facing 48 of the turntable. Preferably an insulating sleeve 68 is circumposed about the electrode 65 to insulate the same from the bracket. The electrode 66 is similarly mounted in recess 69 of the rod 10 and is disposed in vertical alignment with electrode 65. Electrical conductors TI and 12 connect electrodes 65 and 66, respectively, with a suitable source of current.

It should be understood that the present disclosure is for the purpose of illustration only and that this invention includes all modifications and equivalents which fall within the scope of the appended claims.

I claim:

1. The method of tensioning a circular saw or the like which comprises progressively heating an annular portion of the article by passing current through said portion while shifting the path of the current circumferentially along'said annular portion.

2. The method of heat treating an annular portion of a circular saw or like article, which comprises passing current through the portion, producing relative rotation between the path of the current and the article about the axis of the article, and continuing the rotation through a plurality of revolutions so that the annular portion is raised to a higher temperature during each revolution.

3. The method of heat treating a portion of an article which comprises heating the portion by passing current through the article and shifting the path of the current transversely of the path lengthwise of the portion a plurality of times so that the portion is raised to a higher temperature each time.

. ALFRED M. REMINGTON. 

